For customers that purchased a new Mac computer since June 11, the upgrade to Mountain Lion is free from Apple.

Apple brags that Mountain Lion includes over 200 new features -- which are obviously too numerous to list here -- but we'll include just a couple of the highlights:

Full iCloud integration

Game Center, Reminders, and Notes -- all three are staples of iOS, and all three are iCloud-enabled

Messages -- another iOS transplant

Notification Center -- most Mac users got their notifications via Growl, but now Apple is getting into the game with the -- once again -- iOS-esque Notification Center

Dictation

Power Nap -- this feature allows a Mac to still periodically check email and sync iTunes content while in a deep state of sleep. If connected to a power source, the machine will also perform Time Machine backups and download software updates.

Facebook and Twitter -- these two social networks are also baked into the upcoming iOS 6 release

A few sites have posted reviews of Mountain Lion and the consensus is that it's a worthy upgrade to Lion. The Verge's Nilay Patel is overall pleased with the upgrade:

Ultimately, this is pretty easy: you should spend the $20 and upgrade to Mountain Lion, especially if you have a newer Mac. You’ll gain a handful of must-have features, and everything will get faster and smoother. I haven’t really missed Snow Leopard at all since upgrading, which is remarkable considering how much I disliked Lion...

Mountain Lion is the first version of OS X to deeply integrate network services at every level, from storing documents to sharing photos to connecting external displays, and it seems that much lighter for it — as though Apple’s relentless charge into its post-PC era has allowed the OS X team to rethink exactly what a PC is and should be. Mountain Lion isn’t perfect, but it’s a confident, thoughtful step towards the future of desktop computing.

Engadget's Brian Heater acknowledges that Mountain Lion is a bargain upgrade, but also notes that it seems as though OS X is mainly taking a back seat to iOS when it comes to attention/features, and that the operating system is in need of a complete "rethink":

That said, it seems time for Apple to make a bold new pronouncement on the desktop front. The company appears to have most of its resources invested in the mobile side -- and there's no question as to why: the iPhone and iPad have reinvigorated the company, making it a computing player on a scale that no one (save, perhaps, for Jobs himself) could have predicted a decade ago. Still, it might be hard for OS X users not to feel neglected -- many of the latest new features feel a bit like iOS hand-me-downs. When and if Apple rolls out a new operating system this time next year, hopefully we'll be seeing a very different side of Mac OS.

But with a price tag of just $20, Mountain Lion is a no-brainer upgrade for members of the Mac community.

"This is so typical of an Apple faithful. We've been doing this on our PC's for like, I don't know, a decade now? "

Yup, and the Apple narrative is that they invented it... then a year from now the narrative is that others copied it from Apple. the hipocracy of this company and the gullibility of its fans are absolutely amazing.

"Nowadays, security guys break the Mac every single day. Every single day, they come out with a total exploit, your machine can be taken over totally. I dare anybody to do that once a month on the Windows machine." -- Bill Gates